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That manually operated control rod was sophisticated compared to some of the earlier experiments. They used to stack bricks around a chunk of uranium, so the br

That manually operated control rod was sophisticated compared to some of the earlier experiments. They used to stack bricks around a chunk of uranium, so the bricks would reflect neutrons back at the uranium. Eventually, once you stack enough bricks around the uranium it goes super critical and just goes nuts. They used to manually search out this super critical threshold by manually stacking bricks and then slowly move that final brick towards and away from the uranium and watch it balance on the line between sub critical and super critical. One day, someone dropped the brick and there was a blue flash. Lots of neutrons were released that day. People died from radiation exposure soon after. There's also a story about a fuel rod getting jammed, so they tried to force it with a crane and ended up breaking it in half, spilling highly radioactive water all over the place, and then the fuel rod catches on fire because it's not being cooled anymore. It's comical how quickly these disasters escalate. Read https://www.amazon.com/Atomic-Accidents-Meltdowns-Disasters-Mountains/dp/1605986801 https://www.amazon.com/Atomic-Accidents-Meltdowns-Disasters-... , it's accurate and relatively fun given the subject. One of the chapters is titled "The US Government almost never lost nuclear weapons", which I find subtly amusing.

joncrane 5y ago
What about the "demon core?" It was a core of highly radioactive material, and instead of bricks, there were two hollowed out hemispheres made of some metal that reflected the radioactivity. Some guy put one hemisphere below the core, and had another one on top AND WAS USING A SCREWDRIVER to carefully titrate how "closed" the top hemisphere was to the bottom one. His hand slipped and he killed himself and some colleagues. Apparently the "demon core" got its name because it was involved in more than one supercritical accident.
- Buttons840 5y ago
  I think the demon core was the "chunk of uranium" they were stacking bricks around. It's been several years since I read the book so my memory is fuzzy. I think the later experiments used the metal hemispheres instead of bricks.
  - Buttons840 5y ago
    "The core was placed within a stack of neutron-reflective tungsten carbide bricks and the addition of each brick moved the assembly closer to criticality. While attempting to stack another brick around the assembly, Daghlian accidentally dropped it onto the core and thereby caused the core to go well into supercriticality, a self-sustaining critical chain reaction. He quickly moved the brick off the assembly, but received a fatal dose of radiation. He died 25 days later from acute radiation poisoning." https://en.m.wikipedia.org/wiki/Demon_core https://en.m.wikipedia.org/wiki/Demon_core The Wikipedia page describes the 2nd accident as well, involving a screwdriver and metal hemispheres.

joncrane 5y ago

What about the "demon core?" It was a core of highly radioactive material, and instead of bricks, there were two hollowed out hemispheres made of some metal that reflected the radioactivity. Some guy put one hemisphere below the core, and had another one on top AND WAS USING A SCREWDRIVER to carefully titrate how "closed" the top hemisphere was to the bottom one. His hand slipped and he killed himself and some colleagues. Apparently the "demon core" got its name because it was involved in more than one supercritical accident.

Buttons840 5y ago
I think the demon core was the "chunk of uranium" they were stacking bricks around. It's been several years since I read the book so my memory is fuzzy. I think the later experiments used the metal hemispheres instead of bricks.
- Buttons840 5y ago
  "The core was placed within a stack of neutron-reflective tungsten carbide bricks and the addition of each brick moved the assembly closer to criticality. While attempting to stack another brick around the assembly, Daghlian accidentally dropped it onto the core and thereby caused the core to go well into supercriticality, a self-sustaining critical chain reaction. He quickly moved the brick off the assembly, but received a fatal dose of radiation. He died 25 days later from acute radiation poisoning." https://en.m.wikipedia.org/wiki/Demon_core https://en.m.wikipedia.org/wiki/Demon_core The Wikipedia page describes the 2nd accident as well, involving a screwdriver and metal hemispheres.